Apparatus for cementing wells



Sept. 2, 1941.

D. SCARAMUCC I APPARATUS FOR CEMENTING WELLS Filed Aug. 18, 1939 Patented Sept. 2, 1941 UNITED STATES APPARATUS FOR CEMENTING WELLS Domer Scaramucci, Oklahoma City, Okla, assignor to Oil Equipment Engineering Corporation, Oklahoma City, Okla, a corporation of Oklahoma Application August 18, 1939, serial No. 290,891

7 Claims.

The present invention relates to improvement in apparatus for cementing wells, and pertains particularly to the process of cementing in which a cement slurry is forced down a well casing between two plugs which separate it from the well fluid.

The fundamental purpose is to provide apparatus which will enable an operator accurately to retain a predetermined volume of slurry-in the well casing above the shoe. It is customary in cementing casing to retain the upper part of the cement batch within the shoe, because that part is usually soft and contaminated and to insure proper cementing at the lower end of the casing. When the well is completed, the part remaining in the casing can be drilled out easily.

Several methods have been used hitherto for this purpose, but each is subject to some important objection. In one of these, a special baflie is installed at the proper point in a casing string as it is made up to go into the well and the bafile is used in positioning the top plug. An-

' other method employs a measuring line to follow the top plug in its downward travel. The latter method is uncertain where applied to a long string of casing containing heavy drilling fluid, which makes it difficult to detect the plug. The invention herein to be described requires no special casing attachment, or does it need the continuous attention of the operator.

It is a principal object of this invention to provide means for positioning the top cementing plug above the foot of the casing, whereby a definite amount of cement may be retained in the casing.

A further and specific object is the provision of simple and efiicient means which are associated with the top and bottom cementing plugs for retaining a predetermined amount of the cement batch within the lower end of the casing. A more specific object which this invention comprehends is the inclusion of a coloring medium anappreciable distance above the foot of the casing string which will be released before the drill passes through the casing shoe.

The two-plug cementing procedure of this invention utilizes a valve member which is main- 7 That is to say, the two plugs spaced bythe cement slurry are forced down the well casing until the bottom plug reaches the foot of the casing and discharges a. large portion of the cement slurry, whereupon its opening will be 'closed by the valve member and a predetermined volume of inferior or contaminated slurry will bev unable to escape. The coloring medium which has been mentioned may form a part of the valve member and will be liberated by the drill as it goes through the bottom plug. In this alternative or modified embodiment, it is preferable to use an appreciably elongated bottom plug so that the coloring medium may be Fig. 1 represents a side elevation, partly in longitudinal section, of an oil well having 9. casing inserted therein and containing two cementing plugs spaced by a batch of cement slurry;

Fig. 2 is a longitudinal section similar to Fig. 1, with the exception that the plugs and cement have moved to a position farther down the well so casing;

Fig. 3 shows an enlarged vertical cross-section of a valve'member which cooperates with the cementing plugs ofFlgs. l and 2;

Fig. 4 is a fragmentary vertical section of the well and casing, similar to Fig. 2, but illustrating modified forms of valve member and bottom cementing plug;

Fig. 5 is an enlarged vertical section of the valve member of Fig. 4; and

40 Fig. 6 illustrates by means of a vertical section a further embodiment of the valve member.

Referring to Fig. 1, a well bore WB has inserted therein a conventional string of well casing III which is of smaller diameter than the well bore and with which it defines an annular space. A casing head I! adapted for the well cementing operation is secured in place at the upper end of the casing. At its lower end, the casing I0 isprovided with a combination guide and float shoe, the valve means I6 of which is arranged to permit a cement slurry CS to be discharged downwardly therethrough and fill the outer space between the well casing and the lower end portion of the well bore WB, in the manner shown in Fig. 2.

carried to the surface by the drilling fluid be- Attention is now directed to a bottom cementing plug l and a top cementing plug 20 which are spaced .by the cement slurry C8 and separate it from the drilling or well fluid WP within the casing l0; both plugs will ordinarily be formed from wood. The bottom cementing plug it is provided with an opening, illustrated as a bore or passageway 22, which is closed by a rupturable diaphragm and sealing member 24, of rubber or other suitable material. Fig. 1 shows the diaphragm 24 in an unruptured condition and Fig. 2 indicates the ruptured conditlon which is produced by the continued application of downward pressure after the bottom plug II is stopped by the casing shoe It.

A valve member or ball 26 is maintained within the cement slurry CS at substantially the same predetermined distance below the uppermost or top cementing plug 20 by suspending it from the bottom side of the latter with a flexible line I 26 of manila rope or other suitable material. A

connecting eye 20 of brass is secured to the valve member 26 to provide convenient means for attaching the suspending means or line 26. While the ball valve member 26 may be formed from any suitable material which is sufllciently frangible and has a greater specific gravity than the cement slurry, aluminum is preferred.

By means of the measured length of line 20, it is possible for the operator to predetermine and control the volume of the cement slurry which will be trapped within the casing I0 after the valve member 26 has moved relatively into sealing engagement with the upper end of the bore 22 of the bottom plug I 8 (Fig. 2). As illustrated, the valve or closing member 26 is suspended in an aligned position with respect to said plug bore" and is of a size and shape to seal the bore 22 eiiectively when the discharge of cement from the bottom of the casing causes it to move into closed position. It will be understood that the apparatus which has been described in detail requires no further attention from the operator after the top plug 20, carrying the valve member 26 on its lower end, has been placed within the casing I 0 on top of the batch of cement slurry. The operator is then able to force the cement down the casing at maximum speed by means of hydraulic pressure applied to the upper end of the top plug 26, until the discharge of cement through the bottom plug 16 and shoe I4 has been stopped abruptly by the closing action of the valve member 26.

Figs. 4, 5 and 6 illustrate the use of modified forms of valve-members which include the coloring medium. In one form, a hollow spherical valve member 260 of cast aluminum is filled with a coloring agent 261. This valve member 260 is suspended from the line 26 by a connecting eye 200 in the manner previously described.

In order to provide a greater amount of the coloring medium, a hollow cylindrical form of valve member 2600 containing a coloring agent 3000 may be utilized. This valve member 2600 will also be made of a suitable drillable material such as aluminum. The upper end of the valve member 2600 is provided with 9. connecting eye 2620 and it is shaped at its lower end so dye which will give the drilling fluid a distinctive color, e. g., a chromate solution is quite suitable.

when the valve member is provided with a coloring medium, it is desirable to utilize an elongated form of bottom cementing plug I00 having a longitudinal bore 226 and rupturable diaphragm 2 over the bore. With a plug of this length, an intermediate sealing washer I22 of split construction is provided. The elongated plug I00 serves to position the coloring supply well above the shoe (ll) so that the circulating fluid in which the coloring floats or is conveyed will have ample time to return to the surface before the drill has penetrated below the casing shoe.

The operation of the apparatus has been fully described in the preceding paragraphs. Notableimprovements in the cementing of wells are effected by the practice or the present invention. Instead of leaving an indeterminate amount of cement slurry within the casing, with a generous allowance that there shall be too much rather than too little, the exact volume to be retained is predetermined before the pumping of the cement is commenced. After this determination is made by spacing the member which closes the passage of the bottom plug a fixed distance below the top plug, the operation may proceed with maximum speed without the necessity of sounding for the top plug, measuring the volume of pumped fluid, or attaching some special casing device such as a bailie.

Those familiar with this art will understand that the foregoing descriptions of the preferred forms of apparatus are for purposes of illustra tion, and that various changes and modifications can be made which will come within the scope and spirit of the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. Apparatus for use in cementing a well, comprising a well casing, a pair of cementing plugs adapted to be inserted in said casing at the lower and upper ends respectively of a body of cement slurry, a valve member between the plugs, suspending means. for maintaining the valve member substantially the same distance below the top plug, and shoe means positioned at the bottom end of the casing for engagement with the bottom plug to stop its downward movement, said bottom plug having a through passageway arranged to be closed by the valve member when suflicient cement has escaped from the casing to permit the valve memberto move into closing engagement.

2. Apparatus for use in cementing a well, comprising a well casing, a pair of cementing plugs adapted to be inserted in said casing at the lower and upper ends respectively of a body of cement slurry, a ball valve member having a greater specific gravity than the slurry disposed between the plugs, suspending means for maintaining the valve member substantially the same distance below the top plug, and shoe means at the bottom end of the casing and positioned for engagement with the bottom plug to stop its downward movement, said bottom plug having a passageway arranged to be closed by the valve member when suillcient cement slurry has escaped from the casing to permit the valve member to move into closing engagement.

3. The combination which comprises a well casing having a shoe at its lower end; a top cementing plug and a bottom cementing plug adapted to be inserted in the casing at the top and bottom respectively of a body of cement a cement slurry; and a flexible line connected to the top plug and ball valve for suspending the latter a fixed distance below the top of the body of slurry, the bore of the bottom plug and the ball valve being in alignment so that the bore will be closed by the valve when rupture of the diaphragm and discharge of the slurry permit them to engage.

4. Apparatus for use in cementing a well, comprising, a well casing, a pair of cementing plugs adapted to be inserted in said casing at the lower and upper ends respectively of a body of cement slurry, a frangible valve member containing coloring matter disposed between the plugs, a line connected to the top plug and valve member for maintaining the valve member a fixed distance below said top plug, and shoe means at the bottom end of the casing and positioned for engagement with the bottom plug to stop its downward movement, said bottom plug having a bore arranged to be closed by the valve member when suflicient cement slurry has escaped from the casing to permit the valve member to move into closing engagement, and

the coloring matter being releasable as the cement in the casing is drilled.

5. In combination with a well casing, 'a top cementing plug, a valve member, means for suspending the valve member substantially the same distance below the top plug, and a bottom ce-.

menting plug having a through 1 passageway arranged to be closed by the valve member, when engaged thereby.

6. In combination with a well casing, a top cementing plug, a frangible valve member including a color indicator, means for suspending the valve member substantially the same distance below the top plug, and a relatively long bottom cementing plug having a through passageway arranged to be closed at its upper end by the valve member when engaged thereby, so that the color indicator may be released by drilling before the drill reaches the lower end of the bottom plug.

7.'In combination with a well casing, a top cementing plug, a valve member which includes a coloring agent below said top plug, means for suspending the valve member substantially the same distance below the top plug, and a bottom cementing plug having a longitudinal bore arranged to be closed at its upper end by the valve member when engaged thereby.

DOMIER scARAMUccI. 

